1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Linux I2C core
4 *
5 * Copyright (C) 1995-99 Simon G. Vogl
6 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>
7 * Mux support by Rodolfo Giometti <giometti@enneenne.com> and
8 * Michael Lawnick <michael.lawnick.ext@nsn.com>
9 *
10 * Copyright (C) 2013-2017 Wolfram Sang <wsa@kernel.org>
11 */
12
13 #define pr_fmt(fmt) "i2c-core: " fmt
14
15 #include <dt-bindings/i2c/i2c.h>
16 #include <linux/acpi.h>
17 #include <linux/clk/clk-conf.h>
18 #include <linux/completion.h>
19 #include <linux/delay.h>
20 #include <linux/err.h>
21 #include <linux/errno.h>
22 #include <linux/gpio/consumer.h>
23 #include <linux/i2c.h>
24 #include <linux/i2c-smbus.h>
25 #include <linux/idr.h>
26 #include <linux/init.h>
27 #include <linux/interrupt.h>
28 #include <linux/irqflags.h>
29 #include <linux/jump_label.h>
30 #include <linux/kernel.h>
31 #include <linux/module.h>
32 #include <linux/mutex.h>
33 #include <linux/of_device.h>
34 #include <linux/of.h>
35 #include <linux/of_irq.h>
36 #include <linux/pinctrl/consumer.h>
37 #include <linux/pm_domain.h>
38 #include <linux/pm_runtime.h>
39 #include <linux/pm_wakeirq.h>
40 #include <linux/property.h>
41 #include <linux/rwsem.h>
42 #include <linux/slab.h>
43
44 #include "i2c-core.h"
45
46 #define CREATE_TRACE_POINTS
47 #include <trace/events/i2c.h>
48
49 #define I2C_ADDR_OFFSET_TEN_BIT 0xa000
50 #define I2C_ADDR_OFFSET_SLAVE 0x1000
51
52 #define I2C_ADDR_7BITS_MAX 0x77
53 #define I2C_ADDR_7BITS_COUNT (I2C_ADDR_7BITS_MAX + 1)
54
55 #define I2C_ADDR_DEVICE_ID 0x7c
56
57 /*
58 * core_lock protects i2c_adapter_idr, and guarantees that device detection,
59 * deletion of detected devices are serialized
60 */
61 static DEFINE_MUTEX(core_lock);
62 static DEFINE_IDR(i2c_adapter_idr);
63
64 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
65
66 static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key);
67 static bool is_registered;
68
i2c_transfer_trace_reg(void)69 int i2c_transfer_trace_reg(void)
70 {
71 static_branch_inc(&i2c_trace_msg_key);
72 return 0;
73 }
74
i2c_transfer_trace_unreg(void)75 void i2c_transfer_trace_unreg(void)
76 {
77 static_branch_dec(&i2c_trace_msg_key);
78 }
79
i2c_freq_mode_string(u32 bus_freq_hz)80 const char *i2c_freq_mode_string(u32 bus_freq_hz)
81 {
82 switch (bus_freq_hz) {
83 case I2C_MAX_STANDARD_MODE_FREQ:
84 return "Standard Mode (100 kHz)";
85 case I2C_MAX_FAST_MODE_FREQ:
86 return "Fast Mode (400 kHz)";
87 case I2C_MAX_FAST_MODE_PLUS_FREQ:
88 return "Fast Mode Plus (1.0 MHz)";
89 case I2C_MAX_TURBO_MODE_FREQ:
90 return "Turbo Mode (1.4 MHz)";
91 case I2C_MAX_HIGH_SPEED_MODE_FREQ:
92 return "High Speed Mode (3.4 MHz)";
93 case I2C_MAX_ULTRA_FAST_MODE_FREQ:
94 return "Ultra Fast Mode (5.0 MHz)";
95 default:
96 return "Unknown Mode";
97 }
98 }
99 EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
100
i2c_match_id(const struct i2c_device_id * id,const struct i2c_client * client)101 const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
102 const struct i2c_client *client)
103 {
104 if (!(id && client))
105 return NULL;
106
107 while (id->name[0]) {
108 if (strcmp(client->name, id->name) == 0)
109 return id;
110 id++;
111 }
112 return NULL;
113 }
114 EXPORT_SYMBOL_GPL(i2c_match_id);
115
i2c_device_match(struct device * dev,struct device_driver * drv)116 static int i2c_device_match(struct device *dev, struct device_driver *drv)
117 {
118 struct i2c_client *client = i2c_verify_client(dev);
119 struct i2c_driver *driver;
120
121
122 /* Attempt an OF style match */
123 if (i2c_of_match_device(drv->of_match_table, client))
124 return 1;
125
126 /* Then ACPI style match */
127 if (acpi_driver_match_device(dev, drv))
128 return 1;
129
130 driver = to_i2c_driver(drv);
131
132 /* Finally an I2C match */
133 if (i2c_match_id(driver->id_table, client))
134 return 1;
135
136 return 0;
137 }
138
i2c_device_uevent(struct device * dev,struct kobj_uevent_env * env)139 static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
140 {
141 struct i2c_client *client = to_i2c_client(dev);
142 int rc;
143
144 rc = of_device_uevent_modalias(dev, env);
145 if (rc != -ENODEV)
146 return rc;
147
148 rc = acpi_device_uevent_modalias(dev, env);
149 if (rc != -ENODEV)
150 return rc;
151
152 return add_uevent_var(env, "MODALIAS=%s%s", I2C_MODULE_PREFIX, client->name);
153 }
154
155 /* i2c bus recovery routines */
get_scl_gpio_value(struct i2c_adapter * adap)156 static int get_scl_gpio_value(struct i2c_adapter *adap)
157 {
158 return gpiod_get_value_cansleep(adap->bus_recovery_info->scl_gpiod);
159 }
160
set_scl_gpio_value(struct i2c_adapter * adap,int val)161 static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
162 {
163 gpiod_set_value_cansleep(adap->bus_recovery_info->scl_gpiod, val);
164 }
165
get_sda_gpio_value(struct i2c_adapter * adap)166 static int get_sda_gpio_value(struct i2c_adapter *adap)
167 {
168 return gpiod_get_value_cansleep(adap->bus_recovery_info->sda_gpiod);
169 }
170
set_sda_gpio_value(struct i2c_adapter * adap,int val)171 static void set_sda_gpio_value(struct i2c_adapter *adap, int val)
172 {
173 gpiod_set_value_cansleep(adap->bus_recovery_info->sda_gpiod, val);
174 }
175
i2c_generic_bus_free(struct i2c_adapter * adap)176 static int i2c_generic_bus_free(struct i2c_adapter *adap)
177 {
178 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
179 int ret = -EOPNOTSUPP;
180
181 if (bri->get_bus_free)
182 ret = bri->get_bus_free(adap);
183 else if (bri->get_sda)
184 ret = bri->get_sda(adap);
185
186 if (ret < 0)
187 return ret;
188
189 return ret ? 0 : -EBUSY;
190 }
191
192 /*
193 * We are generating clock pulses. ndelay() determines durating of clk pulses.
194 * We will generate clock with rate 100 KHz and so duration of both clock levels
195 * is: delay in ns = (10^6 / 100) / 2
196 */
197 #define RECOVERY_NDELAY 5000
198 #define RECOVERY_CLK_CNT 9
199
i2c_generic_scl_recovery(struct i2c_adapter * adap)200 int i2c_generic_scl_recovery(struct i2c_adapter *adap)
201 {
202 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
203 int i = 0, scl = 1, ret = 0;
204
205 if (bri->prepare_recovery)
206 bri->prepare_recovery(adap);
207 if (bri->pinctrl)
208 pinctrl_select_state(bri->pinctrl, bri->pins_gpio);
209
210 /*
211 * If we can set SDA, we will always create a STOP to ensure additional
212 * pulses will do no harm. This is achieved by letting SDA follow SCL
213 * half a cycle later. Check the 'incomplete_write_byte' fault injector
214 * for details. Note that we must honour tsu:sto, 4us, but lets use 5us
215 * here for simplicity.
216 */
217 bri->set_scl(adap, scl);
218 ndelay(RECOVERY_NDELAY);
219 if (bri->set_sda)
220 bri->set_sda(adap, scl);
221 ndelay(RECOVERY_NDELAY / 2);
222
223 /*
224 * By this time SCL is high, as we need to give 9 falling-rising edges
225 */
226 while (i++ < RECOVERY_CLK_CNT * 2) {
227 if (scl) {
228 /* SCL shouldn't be low here */
229 if (!bri->get_scl(adap)) {
230 dev_err(&adap->dev,
231 "SCL is stuck low, exit recovery\n");
232 ret = -EBUSY;
233 break;
234 }
235 }
236
237 scl = !scl;
238 bri->set_scl(adap, scl);
239 /* Creating STOP again, see above */
240 if (scl) {
241 /* Honour minimum tsu:sto */
242 ndelay(RECOVERY_NDELAY);
243 } else {
244 /* Honour minimum tf and thd:dat */
245 ndelay(RECOVERY_NDELAY / 2);
246 }
247 if (bri->set_sda)
248 bri->set_sda(adap, scl);
249 ndelay(RECOVERY_NDELAY / 2);
250
251 if (scl) {
252 ret = i2c_generic_bus_free(adap);
253 if (ret == 0)
254 break;
255 }
256 }
257
258 /* If we can't check bus status, assume recovery worked */
259 if (ret == -EOPNOTSUPP)
260 ret = 0;
261
262 if (bri->unprepare_recovery)
263 bri->unprepare_recovery(adap);
264 if (bri->pinctrl)
265 pinctrl_select_state(bri->pinctrl, bri->pins_default);
266
267 return ret;
268 }
269 EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
270
i2c_recover_bus(struct i2c_adapter * adap)271 int i2c_recover_bus(struct i2c_adapter *adap)
272 {
273 if (!adap->bus_recovery_info)
274 return -EBUSY;
275
276 dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
277 return adap->bus_recovery_info->recover_bus(adap);
278 }
279 EXPORT_SYMBOL_GPL(i2c_recover_bus);
280
i2c_gpio_init_pinctrl_recovery(struct i2c_adapter * adap)281 static void i2c_gpio_init_pinctrl_recovery(struct i2c_adapter *adap)
282 {
283 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
284 struct device *dev = &adap->dev;
285 struct pinctrl *p = bri->pinctrl;
286
287 /*
288 * we can't change states without pinctrl, so remove the states if
289 * populated
290 */
291 if (!p) {
292 bri->pins_default = NULL;
293 bri->pins_gpio = NULL;
294 return;
295 }
296
297 if (!bri->pins_default) {
298 bri->pins_default = pinctrl_lookup_state(p,
299 PINCTRL_STATE_DEFAULT);
300 if (IS_ERR(bri->pins_default)) {
301 dev_dbg(dev, PINCTRL_STATE_DEFAULT " state not found for GPIO recovery\n");
302 bri->pins_default = NULL;
303 }
304 }
305 if (!bri->pins_gpio) {
306 bri->pins_gpio = pinctrl_lookup_state(p, "gpio");
307 if (IS_ERR(bri->pins_gpio))
308 bri->pins_gpio = pinctrl_lookup_state(p, "recovery");
309
310 if (IS_ERR(bri->pins_gpio)) {
311 dev_dbg(dev, "no gpio or recovery state found for GPIO recovery\n");
312 bri->pins_gpio = NULL;
313 }
314 }
315
316 /* for pinctrl state changes, we need all the information */
317 if (bri->pins_default && bri->pins_gpio) {
318 dev_info(dev, "using pinctrl states for GPIO recovery");
319 } else {
320 bri->pinctrl = NULL;
321 bri->pins_default = NULL;
322 bri->pins_gpio = NULL;
323 }
324 }
325
i2c_gpio_init_generic_recovery(struct i2c_adapter * adap)326 static int i2c_gpio_init_generic_recovery(struct i2c_adapter *adap)
327 {
328 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
329 struct device *dev = &adap->dev;
330 struct gpio_desc *gpiod;
331 int ret = 0;
332
333 /*
334 * don't touch the recovery information if the driver is not using
335 * generic SCL recovery
336 */
337 if (bri->recover_bus && bri->recover_bus != i2c_generic_scl_recovery)
338 return 0;
339
340 /*
341 * pins might be taken as GPIO, so we should inform pinctrl about
342 * this and move the state to GPIO
343 */
344 if (bri->pinctrl)
345 pinctrl_select_state(bri->pinctrl, bri->pins_gpio);
346
347 /*
348 * if there is incomplete or no recovery information, see if generic
349 * GPIO recovery is available
350 */
351 if (!bri->scl_gpiod) {
352 gpiod = devm_gpiod_get(dev, "scl", GPIOD_OUT_HIGH_OPEN_DRAIN);
353 if (PTR_ERR(gpiod) == -EPROBE_DEFER) {
354 ret = -EPROBE_DEFER;
355 goto cleanup_pinctrl_state;
356 }
357 if (!IS_ERR(gpiod)) {
358 bri->scl_gpiod = gpiod;
359 bri->recover_bus = i2c_generic_scl_recovery;
360 dev_info(dev, "using generic GPIOs for recovery\n");
361 }
362 }
363
364 /* SDA GPIOD line is optional, so we care about DEFER only */
365 if (!bri->sda_gpiod) {
366 /*
367 * We have SCL. Pull SCL low and wait a bit so that SDA glitches
368 * have no effect.
369 */
370 gpiod_direction_output(bri->scl_gpiod, 0);
371 udelay(10);
372 gpiod = devm_gpiod_get(dev, "sda", GPIOD_IN);
373
374 /* Wait a bit in case of a SDA glitch, and then release SCL. */
375 udelay(10);
376 gpiod_direction_output(bri->scl_gpiod, 1);
377
378 if (PTR_ERR(gpiod) == -EPROBE_DEFER) {
379 ret = -EPROBE_DEFER;
380 goto cleanup_pinctrl_state;
381 }
382 if (!IS_ERR(gpiod))
383 bri->sda_gpiod = gpiod;
384 }
385
386 cleanup_pinctrl_state:
387 /* change the state of the pins back to their default state */
388 if (bri->pinctrl)
389 pinctrl_select_state(bri->pinctrl, bri->pins_default);
390
391 return ret;
392 }
393
i2c_gpio_init_recovery(struct i2c_adapter * adap)394 static int i2c_gpio_init_recovery(struct i2c_adapter *adap)
395 {
396 i2c_gpio_init_pinctrl_recovery(adap);
397 return i2c_gpio_init_generic_recovery(adap);
398 }
399
i2c_init_recovery(struct i2c_adapter * adap)400 static int i2c_init_recovery(struct i2c_adapter *adap)
401 {
402 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
403 bool is_error_level = true;
404 char *err_str;
405
406 if (!bri)
407 return 0;
408
409 if (i2c_gpio_init_recovery(adap) == -EPROBE_DEFER)
410 return -EPROBE_DEFER;
411
412 if (!bri->recover_bus) {
413 err_str = "no suitable method provided";
414 is_error_level = false;
415 goto err;
416 }
417
418 if (bri->scl_gpiod && bri->recover_bus == i2c_generic_scl_recovery) {
419 bri->get_scl = get_scl_gpio_value;
420 bri->set_scl = set_scl_gpio_value;
421 if (bri->sda_gpiod) {
422 bri->get_sda = get_sda_gpio_value;
423 /* FIXME: add proper flag instead of '0' once available */
424 if (gpiod_get_direction(bri->sda_gpiod) == 0)
425 bri->set_sda = set_sda_gpio_value;
426 }
427 } else if (bri->recover_bus == i2c_generic_scl_recovery) {
428 /* Generic SCL recovery */
429 if (!bri->set_scl || !bri->get_scl) {
430 err_str = "no {get|set}_scl() found";
431 goto err;
432 }
433 if (!bri->set_sda && !bri->get_sda) {
434 err_str = "either get_sda() or set_sda() needed";
435 goto err;
436 }
437 }
438
439 return 0;
440 err:
441 if (is_error_level)
442 dev_err(&adap->dev, "Not using recovery: %s\n", err_str);
443 else
444 dev_dbg(&adap->dev, "Not using recovery: %s\n", err_str);
445 adap->bus_recovery_info = NULL;
446
447 return -EINVAL;
448 }
449
i2c_smbus_host_notify_to_irq(const struct i2c_client * client)450 static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
451 {
452 struct i2c_adapter *adap = client->adapter;
453 unsigned int irq;
454
455 if (!adap->host_notify_domain)
456 return -ENXIO;
457
458 if (client->flags & I2C_CLIENT_TEN)
459 return -EINVAL;
460
461 irq = irq_create_mapping(adap->host_notify_domain, client->addr);
462
463 return irq > 0 ? irq : -ENXIO;
464 }
465
i2c_device_probe(struct device * dev)466 static int i2c_device_probe(struct device *dev)
467 {
468 struct i2c_client *client = i2c_verify_client(dev);
469 struct i2c_driver *driver;
470 bool do_power_on;
471 int status;
472
473 if (!client)
474 return 0;
475
476 client->irq = client->init_irq;
477
478 if (!client->irq) {
479 int irq = -ENOENT;
480
481 if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
482 dev_dbg(dev, "Using Host Notify IRQ\n");
483 /* Keep adapter active when Host Notify is required */
484 pm_runtime_get_sync(&client->adapter->dev);
485 irq = i2c_smbus_host_notify_to_irq(client);
486 } else if (dev->of_node) {
487 irq = of_irq_get_byname(dev->of_node, "irq");
488 if (irq == -EINVAL || irq == -ENODATA)
489 irq = of_irq_get(dev->of_node, 0);
490 } else if (ACPI_COMPANION(dev)) {
491 bool wake_capable;
492
493 irq = i2c_acpi_get_irq(client, &wake_capable);
494 if (irq > 0 && wake_capable)
495 client->flags |= I2C_CLIENT_WAKE;
496 }
497 if (irq == -EPROBE_DEFER) {
498 status = irq;
499 goto put_sync_adapter;
500 }
501
502 if (irq < 0)
503 irq = 0;
504
505 client->irq = irq;
506 }
507
508 driver = to_i2c_driver(dev->driver);
509
510 /*
511 * An I2C ID table is not mandatory, if and only if, a suitable OF
512 * or ACPI ID table is supplied for the probing device.
513 */
514 if (!driver->id_table &&
515 !acpi_driver_match_device(dev, dev->driver) &&
516 !i2c_of_match_device(dev->driver->of_match_table, client)) {
517 status = -ENODEV;
518 goto put_sync_adapter;
519 }
520
521 if (client->flags & I2C_CLIENT_WAKE) {
522 int wakeirq;
523
524 wakeirq = of_irq_get_byname(dev->of_node, "wakeup");
525 if (wakeirq == -EPROBE_DEFER) {
526 status = wakeirq;
527 goto put_sync_adapter;
528 }
529
530 device_init_wakeup(&client->dev, true);
531
532 if (wakeirq > 0 && wakeirq != client->irq)
533 status = dev_pm_set_dedicated_wake_irq(dev, wakeirq);
534 else if (client->irq > 0)
535 status = dev_pm_set_wake_irq(dev, client->irq);
536 else
537 status = 0;
538
539 if (status)
540 dev_warn(&client->dev, "failed to set up wakeup irq\n");
541 }
542
543 dev_dbg(dev, "probe\n");
544
545 status = of_clk_set_defaults(dev->of_node, false);
546 if (status < 0)
547 goto err_clear_wakeup_irq;
548
549 do_power_on = !i2c_acpi_waive_d0_probe(dev);
550 status = dev_pm_domain_attach(&client->dev, do_power_on);
551 if (status)
552 goto err_clear_wakeup_irq;
553
554 client->devres_group_id = devres_open_group(&client->dev, NULL,
555 GFP_KERNEL);
556 if (!client->devres_group_id) {
557 status = -ENOMEM;
558 goto err_detach_pm_domain;
559 }
560
561 /*
562 * When there are no more users of probe(),
563 * rename probe_new to probe.
564 */
565 if (driver->probe_new)
566 status = driver->probe_new(client);
567 else if (driver->probe)
568 status = driver->probe(client,
569 i2c_match_id(driver->id_table, client));
570 else
571 status = -EINVAL;
572
573 /*
574 * Note that we are not closing the devres group opened above so
575 * even resources that were attached to the device after probe is
576 * run are released when i2c_device_remove() is executed. This is
577 * needed as some drivers would allocate additional resources,
578 * for example when updating firmware.
579 */
580
581 if (status)
582 goto err_release_driver_resources;
583
584 return 0;
585
586 err_release_driver_resources:
587 devres_release_group(&client->dev, client->devres_group_id);
588 err_detach_pm_domain:
589 dev_pm_domain_detach(&client->dev, do_power_on);
590 err_clear_wakeup_irq:
591 dev_pm_clear_wake_irq(&client->dev);
592 device_init_wakeup(&client->dev, false);
593 put_sync_adapter:
594 if (client->flags & I2C_CLIENT_HOST_NOTIFY)
595 pm_runtime_put_sync(&client->adapter->dev);
596
597 return status;
598 }
599
i2c_device_remove(struct device * dev)600 static void i2c_device_remove(struct device *dev)
601 {
602 struct i2c_client *client = to_i2c_client(dev);
603 struct i2c_driver *driver;
604
605 driver = to_i2c_driver(dev->driver);
606 if (driver->remove) {
607 dev_dbg(dev, "remove\n");
608
609 driver->remove(client);
610 }
611
612 devres_release_group(&client->dev, client->devres_group_id);
613
614 dev_pm_domain_detach(&client->dev, true);
615
616 dev_pm_clear_wake_irq(&client->dev);
617 device_init_wakeup(&client->dev, false);
618
619 client->irq = 0;
620 if (client->flags & I2C_CLIENT_HOST_NOTIFY)
621 pm_runtime_put(&client->adapter->dev);
622 }
623
i2c_device_shutdown(struct device * dev)624 static void i2c_device_shutdown(struct device *dev)
625 {
626 struct i2c_client *client = i2c_verify_client(dev);
627 struct i2c_driver *driver;
628
629 if (!client || !dev->driver)
630 return;
631 driver = to_i2c_driver(dev->driver);
632 if (driver->shutdown)
633 driver->shutdown(client);
634 else if (client->irq > 0)
635 disable_irq(client->irq);
636 }
637
i2c_client_dev_release(struct device * dev)638 static void i2c_client_dev_release(struct device *dev)
639 {
640 kfree(to_i2c_client(dev));
641 }
642
643 static ssize_t
name_show(struct device * dev,struct device_attribute * attr,char * buf)644 name_show(struct device *dev, struct device_attribute *attr, char *buf)
645 {
646 return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
647 to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
648 }
649 static DEVICE_ATTR_RO(name);
650
651 static ssize_t
modalias_show(struct device * dev,struct device_attribute * attr,char * buf)652 modalias_show(struct device *dev, struct device_attribute *attr, char *buf)
653 {
654 struct i2c_client *client = to_i2c_client(dev);
655 int len;
656
657 len = of_device_modalias(dev, buf, PAGE_SIZE);
658 if (len != -ENODEV)
659 return len;
660
661 len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
662 if (len != -ENODEV)
663 return len;
664
665 return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
666 }
667 static DEVICE_ATTR_RO(modalias);
668
669 static struct attribute *i2c_dev_attrs[] = {
670 &dev_attr_name.attr,
671 /* modalias helps coldplug: modprobe $(cat .../modalias) */
672 &dev_attr_modalias.attr,
673 NULL
674 };
675 ATTRIBUTE_GROUPS(i2c_dev);
676
677 struct bus_type i2c_bus_type = {
678 .name = "i2c",
679 .match = i2c_device_match,
680 .probe = i2c_device_probe,
681 .remove = i2c_device_remove,
682 .shutdown = i2c_device_shutdown,
683 };
684 EXPORT_SYMBOL_GPL(i2c_bus_type);
685
686 struct device_type i2c_client_type = {
687 .groups = i2c_dev_groups,
688 .uevent = i2c_device_uevent,
689 .release = i2c_client_dev_release,
690 };
691 EXPORT_SYMBOL_GPL(i2c_client_type);
692
693
694 /**
695 * i2c_verify_client - return parameter as i2c_client, or NULL
696 * @dev: device, probably from some driver model iterator
697 *
698 * When traversing the driver model tree, perhaps using driver model
699 * iterators like @device_for_each_child(), you can't assume very much
700 * about the nodes you find. Use this function to avoid oopses caused
701 * by wrongly treating some non-I2C device as an i2c_client.
702 */
i2c_verify_client(struct device * dev)703 struct i2c_client *i2c_verify_client(struct device *dev)
704 {
705 return (dev->type == &i2c_client_type)
706 ? to_i2c_client(dev)
707 : NULL;
708 }
709 EXPORT_SYMBOL(i2c_verify_client);
710
711
712 /* Return a unique address which takes the flags of the client into account */
i2c_encode_flags_to_addr(struct i2c_client * client)713 static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client)
714 {
715 unsigned short addr = client->addr;
716
717 /* For some client flags, add an arbitrary offset to avoid collisions */
718 if (client->flags & I2C_CLIENT_TEN)
719 addr |= I2C_ADDR_OFFSET_TEN_BIT;
720
721 if (client->flags & I2C_CLIENT_SLAVE)
722 addr |= I2C_ADDR_OFFSET_SLAVE;
723
724 return addr;
725 }
726
727 /* This is a permissive address validity check, I2C address map constraints
728 * are purposely not enforced, except for the general call address. */
i2c_check_addr_validity(unsigned int addr,unsigned short flags)729 static int i2c_check_addr_validity(unsigned int addr, unsigned short flags)
730 {
731 if (flags & I2C_CLIENT_TEN) {
732 /* 10-bit address, all values are valid */
733 if (addr > 0x3ff)
734 return -EINVAL;
735 } else {
736 /* 7-bit address, reject the general call address */
737 if (addr == 0x00 || addr > 0x7f)
738 return -EINVAL;
739 }
740 return 0;
741 }
742
743 /* And this is a strict address validity check, used when probing. If a
744 * device uses a reserved address, then it shouldn't be probed. 7-bit
745 * addressing is assumed, 10-bit address devices are rare and should be
746 * explicitly enumerated. */
i2c_check_7bit_addr_validity_strict(unsigned short addr)747 int i2c_check_7bit_addr_validity_strict(unsigned short addr)
748 {
749 /*
750 * Reserved addresses per I2C specification:
751 * 0x00 General call address / START byte
752 * 0x01 CBUS address
753 * 0x02 Reserved for different bus format
754 * 0x03 Reserved for future purposes
755 * 0x04-0x07 Hs-mode master code
756 * 0x78-0x7b 10-bit slave addressing
757 * 0x7c-0x7f Reserved for future purposes
758 */
759 if (addr < 0x08 || addr > 0x77)
760 return -EINVAL;
761 return 0;
762 }
763
__i2c_check_addr_busy(struct device * dev,void * addrp)764 static int __i2c_check_addr_busy(struct device *dev, void *addrp)
765 {
766 struct i2c_client *client = i2c_verify_client(dev);
767 int addr = *(int *)addrp;
768
769 if (client && i2c_encode_flags_to_addr(client) == addr)
770 return -EBUSY;
771 return 0;
772 }
773
774 /* walk up mux tree */
i2c_check_mux_parents(struct i2c_adapter * adapter,int addr)775 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
776 {
777 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
778 int result;
779
780 result = device_for_each_child(&adapter->dev, &addr,
781 __i2c_check_addr_busy);
782
783 if (!result && parent)
784 result = i2c_check_mux_parents(parent, addr);
785
786 return result;
787 }
788
789 /* recurse down mux tree */
i2c_check_mux_children(struct device * dev,void * addrp)790 static int i2c_check_mux_children(struct device *dev, void *addrp)
791 {
792 int result;
793
794 if (dev->type == &i2c_adapter_type)
795 result = device_for_each_child(dev, addrp,
796 i2c_check_mux_children);
797 else
798 result = __i2c_check_addr_busy(dev, addrp);
799
800 return result;
801 }
802
i2c_check_addr_busy(struct i2c_adapter * adapter,int addr)803 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
804 {
805 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
806 int result = 0;
807
808 if (parent)
809 result = i2c_check_mux_parents(parent, addr);
810
811 if (!result)
812 result = device_for_each_child(&adapter->dev, &addr,
813 i2c_check_mux_children);
814
815 return result;
816 }
817
818 /**
819 * i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment
820 * @adapter: Target I2C bus segment
821 * @flags: I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT
822 * locks only this branch in the adapter tree
823 */
i2c_adapter_lock_bus(struct i2c_adapter * adapter,unsigned int flags)824 static void i2c_adapter_lock_bus(struct i2c_adapter *adapter,
825 unsigned int flags)
826 {
827 rt_mutex_lock_nested(&adapter->bus_lock, i2c_adapter_depth(adapter));
828 }
829
830 /**
831 * i2c_adapter_trylock_bus - Try to get exclusive access to an I2C bus segment
832 * @adapter: Target I2C bus segment
833 * @flags: I2C_LOCK_ROOT_ADAPTER trylocks the root i2c adapter, I2C_LOCK_SEGMENT
834 * trylocks only this branch in the adapter tree
835 */
i2c_adapter_trylock_bus(struct i2c_adapter * adapter,unsigned int flags)836 static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter,
837 unsigned int flags)
838 {
839 return rt_mutex_trylock(&adapter->bus_lock);
840 }
841
842 /**
843 * i2c_adapter_unlock_bus - Release exclusive access to an I2C bus segment
844 * @adapter: Target I2C bus segment
845 * @flags: I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENT
846 * unlocks only this branch in the adapter tree
847 */
i2c_adapter_unlock_bus(struct i2c_adapter * adapter,unsigned int flags)848 static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter,
849 unsigned int flags)
850 {
851 rt_mutex_unlock(&adapter->bus_lock);
852 }
853
i2c_dev_set_name(struct i2c_adapter * adap,struct i2c_client * client,struct i2c_board_info const * info)854 static void i2c_dev_set_name(struct i2c_adapter *adap,
855 struct i2c_client *client,
856 struct i2c_board_info const *info)
857 {
858 struct acpi_device *adev = ACPI_COMPANION(&client->dev);
859
860 if (info && info->dev_name) {
861 dev_set_name(&client->dev, "i2c-%s", info->dev_name);
862 return;
863 }
864
865 if (adev) {
866 dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev));
867 return;
868 }
869
870 dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
871 i2c_encode_flags_to_addr(client));
872 }
873
i2c_dev_irq_from_resources(const struct resource * resources,unsigned int num_resources)874 int i2c_dev_irq_from_resources(const struct resource *resources,
875 unsigned int num_resources)
876 {
877 struct irq_data *irqd;
878 int i;
879
880 for (i = 0; i < num_resources; i++) {
881 const struct resource *r = &resources[i];
882
883 if (resource_type(r) != IORESOURCE_IRQ)
884 continue;
885
886 if (r->flags & IORESOURCE_BITS) {
887 irqd = irq_get_irq_data(r->start);
888 if (!irqd)
889 break;
890
891 irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
892 }
893
894 return r->start;
895 }
896
897 return 0;
898 }
899
900 /**
901 * i2c_new_client_device - instantiate an i2c device
902 * @adap: the adapter managing the device
903 * @info: describes one I2C device; bus_num is ignored
904 * Context: can sleep
905 *
906 * Create an i2c device. Binding is handled through driver model
907 * probe()/remove() methods. A driver may be bound to this device when we
908 * return from this function, or any later moment (e.g. maybe hotplugging will
909 * load the driver module). This call is not appropriate for use by mainboard
910 * initialization logic, which usually runs during an arch_initcall() long
911 * before any i2c_adapter could exist.
912 *
913 * This returns the new i2c client, which may be saved for later use with
914 * i2c_unregister_device(); or an ERR_PTR to describe the error.
915 */
916 struct i2c_client *
i2c_new_client_device(struct i2c_adapter * adap,struct i2c_board_info const * info)917 i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
918 {
919 struct i2c_client *client;
920 bool need_put = false;
921 int status;
922
923 client = kzalloc(sizeof *client, GFP_KERNEL);
924 if (!client)
925 return ERR_PTR(-ENOMEM);
926
927 client->adapter = adap;
928
929 client->dev.platform_data = info->platform_data;
930 client->flags = info->flags;
931 client->addr = info->addr;
932
933 client->init_irq = info->irq;
934 if (!client->init_irq)
935 client->init_irq = i2c_dev_irq_from_resources(info->resources,
936 info->num_resources);
937
938 strscpy(client->name, info->type, sizeof(client->name));
939
940 status = i2c_check_addr_validity(client->addr, client->flags);
941 if (status) {
942 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
943 client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
944 goto out_err_silent;
945 }
946
947 /* Check for address business */
948 status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client));
949 if (status)
950 goto out_err;
951
952 client->dev.parent = &client->adapter->dev;
953 client->dev.bus = &i2c_bus_type;
954 client->dev.type = &i2c_client_type;
955 client->dev.of_node = of_node_get(info->of_node);
956 client->dev.fwnode = info->fwnode;
957
958 device_enable_async_suspend(&client->dev);
959
960 if (info->swnode) {
961 status = device_add_software_node(&client->dev, info->swnode);
962 if (status) {
963 dev_err(&adap->dev,
964 "Failed to add software node to client %s: %d\n",
965 client->name, status);
966 goto out_err_put_of_node;
967 }
968 }
969
970 i2c_dev_set_name(adap, client, info);
971 status = device_register(&client->dev);
972 if (status)
973 goto out_remove_swnode;
974
975 dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
976 client->name, dev_name(&client->dev));
977
978 return client;
979
980 out_remove_swnode:
981 device_remove_software_node(&client->dev);
982 need_put = true;
983 out_err_put_of_node:
984 of_node_put(info->of_node);
985 out_err:
986 dev_err(&adap->dev,
987 "Failed to register i2c client %s at 0x%02x (%d)\n",
988 client->name, client->addr, status);
989 out_err_silent:
990 if (need_put)
991 put_device(&client->dev);
992 else
993 kfree(client);
994 return ERR_PTR(status);
995 }
996 EXPORT_SYMBOL_GPL(i2c_new_client_device);
997
998 /**
999 * i2c_unregister_device - reverse effect of i2c_new_*_device()
1000 * @client: value returned from i2c_new_*_device()
1001 * Context: can sleep
1002 */
i2c_unregister_device(struct i2c_client * client)1003 void i2c_unregister_device(struct i2c_client *client)
1004 {
1005 if (IS_ERR_OR_NULL(client))
1006 return;
1007
1008 if (client->dev.of_node) {
1009 of_node_clear_flag(client->dev.of_node, OF_POPULATED);
1010 of_node_put(client->dev.of_node);
1011 }
1012
1013 if (ACPI_COMPANION(&client->dev))
1014 acpi_device_clear_enumerated(ACPI_COMPANION(&client->dev));
1015 device_remove_software_node(&client->dev);
1016 device_unregister(&client->dev);
1017 }
1018 EXPORT_SYMBOL_GPL(i2c_unregister_device);
1019
1020
1021 static const struct i2c_device_id dummy_id[] = {
1022 { "dummy", 0 },
1023 { },
1024 };
1025
dummy_probe(struct i2c_client * client,const struct i2c_device_id * id)1026 static int dummy_probe(struct i2c_client *client,
1027 const struct i2c_device_id *id)
1028 {
1029 return 0;
1030 }
1031
1032 static struct i2c_driver dummy_driver = {
1033 .driver.name = "dummy",
1034 .probe = dummy_probe,
1035 .id_table = dummy_id,
1036 };
1037
1038 /**
1039 * i2c_new_dummy_device - return a new i2c device bound to a dummy driver
1040 * @adapter: the adapter managing the device
1041 * @address: seven bit address to be used
1042 * Context: can sleep
1043 *
1044 * This returns an I2C client bound to the "dummy" driver, intended for use
1045 * with devices that consume multiple addresses. Examples of such chips
1046 * include various EEPROMS (like 24c04 and 24c08 models).
1047 *
1048 * These dummy devices have two main uses. First, most I2C and SMBus calls
1049 * except i2c_transfer() need a client handle; the dummy will be that handle.
1050 * And second, this prevents the specified address from being bound to a
1051 * different driver.
1052 *
1053 * This returns the new i2c client, which should be saved for later use with
1054 * i2c_unregister_device(); or an ERR_PTR to describe the error.
1055 */
i2c_new_dummy_device(struct i2c_adapter * adapter,u16 address)1056 struct i2c_client *i2c_new_dummy_device(struct i2c_adapter *adapter, u16 address)
1057 {
1058 struct i2c_board_info info = {
1059 I2C_BOARD_INFO("dummy", address),
1060 };
1061
1062 return i2c_new_client_device(adapter, &info);
1063 }
1064 EXPORT_SYMBOL_GPL(i2c_new_dummy_device);
1065
devm_i2c_release_dummy(void * client)1066 static void devm_i2c_release_dummy(void *client)
1067 {
1068 i2c_unregister_device(client);
1069 }
1070
1071 /**
1072 * devm_i2c_new_dummy_device - return a new i2c device bound to a dummy driver
1073 * @dev: device the managed resource is bound to
1074 * @adapter: the adapter managing the device
1075 * @address: seven bit address to be used
1076 * Context: can sleep
1077 *
1078 * This is the device-managed version of @i2c_new_dummy_device. It returns the
1079 * new i2c client or an ERR_PTR in case of an error.
1080 */
devm_i2c_new_dummy_device(struct device * dev,struct i2c_adapter * adapter,u16 address)1081 struct i2c_client *devm_i2c_new_dummy_device(struct device *dev,
1082 struct i2c_adapter *adapter,
1083 u16 address)
1084 {
1085 struct i2c_client *client;
1086 int ret;
1087
1088 client = i2c_new_dummy_device(adapter, address);
1089 if (IS_ERR(client))
1090 return client;
1091
1092 ret = devm_add_action_or_reset(dev, devm_i2c_release_dummy, client);
1093 if (ret)
1094 return ERR_PTR(ret);
1095
1096 return client;
1097 }
1098 EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device);
1099
1100 /**
1101 * i2c_new_ancillary_device - Helper to get the instantiated secondary address
1102 * and create the associated device
1103 * @client: Handle to the primary client
1104 * @name: Handle to specify which secondary address to get
1105 * @default_addr: Used as a fallback if no secondary address was specified
1106 * Context: can sleep
1107 *
1108 * I2C clients can be composed of multiple I2C slaves bound together in a single
1109 * component. The I2C client driver then binds to the master I2C slave and needs
1110 * to create I2C dummy clients to communicate with all the other slaves.
1111 *
1112 * This function creates and returns an I2C dummy client whose I2C address is
1113 * retrieved from the platform firmware based on the given slave name. If no
1114 * address is specified by the firmware default_addr is used.
1115 *
1116 * On DT-based platforms the address is retrieved from the "reg" property entry
1117 * cell whose "reg-names" value matches the slave name.
1118 *
1119 * This returns the new i2c client, which should be saved for later use with
1120 * i2c_unregister_device(); or an ERR_PTR to describe the error.
1121 */
i2c_new_ancillary_device(struct i2c_client * client,const char * name,u16 default_addr)1122 struct i2c_client *i2c_new_ancillary_device(struct i2c_client *client,
1123 const char *name,
1124 u16 default_addr)
1125 {
1126 struct device_node *np = client->dev.of_node;
1127 u32 addr = default_addr;
1128 int i;
1129
1130 if (np) {
1131 i = of_property_match_string(np, "reg-names", name);
1132 if (i >= 0)
1133 of_property_read_u32_index(np, "reg", i, &addr);
1134 }
1135
1136 dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr);
1137 return i2c_new_dummy_device(client->adapter, addr);
1138 }
1139 EXPORT_SYMBOL_GPL(i2c_new_ancillary_device);
1140
1141 /* ------------------------------------------------------------------------- */
1142
1143 /* I2C bus adapters -- one roots each I2C or SMBUS segment */
1144
i2c_adapter_dev_release(struct device * dev)1145 static void i2c_adapter_dev_release(struct device *dev)
1146 {
1147 struct i2c_adapter *adap = to_i2c_adapter(dev);
1148 complete(&adap->dev_released);
1149 }
1150
i2c_adapter_depth(struct i2c_adapter * adapter)1151 unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
1152 {
1153 unsigned int depth = 0;
1154
1155 while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
1156 depth++;
1157
1158 WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES,
1159 "adapter depth exceeds lockdep subclass limit\n");
1160
1161 return depth;
1162 }
1163 EXPORT_SYMBOL_GPL(i2c_adapter_depth);
1164
1165 /*
1166 * Let users instantiate I2C devices through sysfs. This can be used when
1167 * platform initialization code doesn't contain the proper data for
1168 * whatever reason. Also useful for drivers that do device detection and
1169 * detection fails, either because the device uses an unexpected address,
1170 * or this is a compatible device with different ID register values.
1171 *
1172 * Parameter checking may look overzealous, but we really don't want
1173 * the user to provide incorrect parameters.
1174 */
1175 static ssize_t
new_device_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)1176 new_device_store(struct device *dev, struct device_attribute *attr,
1177 const char *buf, size_t count)
1178 {
1179 struct i2c_adapter *adap = to_i2c_adapter(dev);
1180 struct i2c_board_info info;
1181 struct i2c_client *client;
1182 char *blank, end;
1183 int res;
1184
1185 memset(&info, 0, sizeof(struct i2c_board_info));
1186
1187 blank = strchr(buf, ' ');
1188 if (!blank) {
1189 dev_err(dev, "%s: Missing parameters\n", "new_device");
1190 return -EINVAL;
1191 }
1192 if (blank - buf > I2C_NAME_SIZE - 1) {
1193 dev_err(dev, "%s: Invalid device name\n", "new_device");
1194 return -EINVAL;
1195 }
1196 memcpy(info.type, buf, blank - buf);
1197
1198 /* Parse remaining parameters, reject extra parameters */
1199 res = sscanf(++blank, "%hi%c", &info.addr, &end);
1200 if (res < 1) {
1201 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
1202 return -EINVAL;
1203 }
1204 if (res > 1 && end != '\n') {
1205 dev_err(dev, "%s: Extra parameters\n", "new_device");
1206 return -EINVAL;
1207 }
1208
1209 if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) {
1210 info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT;
1211 info.flags |= I2C_CLIENT_TEN;
1212 }
1213
1214 if (info.addr & I2C_ADDR_OFFSET_SLAVE) {
1215 info.addr &= ~I2C_ADDR_OFFSET_SLAVE;
1216 info.flags |= I2C_CLIENT_SLAVE;
1217 }
1218
1219 client = i2c_new_client_device(adap, &info);
1220 if (IS_ERR(client))
1221 return PTR_ERR(client);
1222
1223 /* Keep track of the added device */
1224 mutex_lock(&adap->userspace_clients_lock);
1225 list_add_tail(&client->detected, &adap->userspace_clients);
1226 mutex_unlock(&adap->userspace_clients_lock);
1227 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
1228 info.type, info.addr);
1229
1230 return count;
1231 }
1232 static DEVICE_ATTR_WO(new_device);
1233
1234 /*
1235 * And of course let the users delete the devices they instantiated, if
1236 * they got it wrong. This interface can only be used to delete devices
1237 * instantiated by i2c_sysfs_new_device above. This guarantees that we
1238 * don't delete devices to which some kernel code still has references.
1239 *
1240 * Parameter checking may look overzealous, but we really don't want
1241 * the user to delete the wrong device.
1242 */
1243 static ssize_t
delete_device_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)1244 delete_device_store(struct device *dev, struct device_attribute *attr,
1245 const char *buf, size_t count)
1246 {
1247 struct i2c_adapter *adap = to_i2c_adapter(dev);
1248 struct i2c_client *client, *next;
1249 unsigned short addr;
1250 char end;
1251 int res;
1252
1253 /* Parse parameters, reject extra parameters */
1254 res = sscanf(buf, "%hi%c", &addr, &end);
1255 if (res < 1) {
1256 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
1257 return -EINVAL;
1258 }
1259 if (res > 1 && end != '\n') {
1260 dev_err(dev, "%s: Extra parameters\n", "delete_device");
1261 return -EINVAL;
1262 }
1263
1264 /* Make sure the device was added through sysfs */
1265 res = -ENOENT;
1266 mutex_lock_nested(&adap->userspace_clients_lock,
1267 i2c_adapter_depth(adap));
1268 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1269 detected) {
1270 if (i2c_encode_flags_to_addr(client) == addr) {
1271 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
1272 "delete_device", client->name, client->addr);
1273
1274 list_del(&client->detected);
1275 i2c_unregister_device(client);
1276 res = count;
1277 break;
1278 }
1279 }
1280 mutex_unlock(&adap->userspace_clients_lock);
1281
1282 if (res < 0)
1283 dev_err(dev, "%s: Can't find device in list\n",
1284 "delete_device");
1285 return res;
1286 }
1287 static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
1288 delete_device_store);
1289
1290 static struct attribute *i2c_adapter_attrs[] = {
1291 &dev_attr_name.attr,
1292 &dev_attr_new_device.attr,
1293 &dev_attr_delete_device.attr,
1294 NULL
1295 };
1296 ATTRIBUTE_GROUPS(i2c_adapter);
1297
1298 struct device_type i2c_adapter_type = {
1299 .groups = i2c_adapter_groups,
1300 .release = i2c_adapter_dev_release,
1301 };
1302 EXPORT_SYMBOL_GPL(i2c_adapter_type);
1303
1304 /**
1305 * i2c_verify_adapter - return parameter as i2c_adapter or NULL
1306 * @dev: device, probably from some driver model iterator
1307 *
1308 * When traversing the driver model tree, perhaps using driver model
1309 * iterators like @device_for_each_child(), you can't assume very much
1310 * about the nodes you find. Use this function to avoid oopses caused
1311 * by wrongly treating some non-I2C device as an i2c_adapter.
1312 */
i2c_verify_adapter(struct device * dev)1313 struct i2c_adapter *i2c_verify_adapter(struct device *dev)
1314 {
1315 return (dev->type == &i2c_adapter_type)
1316 ? to_i2c_adapter(dev)
1317 : NULL;
1318 }
1319 EXPORT_SYMBOL(i2c_verify_adapter);
1320
1321 #ifdef CONFIG_I2C_COMPAT
1322 static struct class_compat *i2c_adapter_compat_class;
1323 #endif
1324
i2c_scan_static_board_info(struct i2c_adapter * adapter)1325 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
1326 {
1327 struct i2c_devinfo *devinfo;
1328
1329 down_read(&__i2c_board_lock);
1330 list_for_each_entry(devinfo, &__i2c_board_list, list) {
1331 if (devinfo->busnum == adapter->nr &&
1332 IS_ERR(i2c_new_client_device(adapter, &devinfo->board_info)))
1333 dev_err(&adapter->dev,
1334 "Can't create device at 0x%02x\n",
1335 devinfo->board_info.addr);
1336 }
1337 up_read(&__i2c_board_lock);
1338 }
1339
i2c_do_add_adapter(struct i2c_driver * driver,struct i2c_adapter * adap)1340 static int i2c_do_add_adapter(struct i2c_driver *driver,
1341 struct i2c_adapter *adap)
1342 {
1343 /* Detect supported devices on that bus, and instantiate them */
1344 i2c_detect(adap, driver);
1345
1346 return 0;
1347 }
1348
__process_new_adapter(struct device_driver * d,void * data)1349 static int __process_new_adapter(struct device_driver *d, void *data)
1350 {
1351 return i2c_do_add_adapter(to_i2c_driver(d), data);
1352 }
1353
1354 static const struct i2c_lock_operations i2c_adapter_lock_ops = {
1355 .lock_bus = i2c_adapter_lock_bus,
1356 .trylock_bus = i2c_adapter_trylock_bus,
1357 .unlock_bus = i2c_adapter_unlock_bus,
1358 };
1359
i2c_host_notify_irq_teardown(struct i2c_adapter * adap)1360 static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap)
1361 {
1362 struct irq_domain *domain = adap->host_notify_domain;
1363 irq_hw_number_t hwirq;
1364
1365 if (!domain)
1366 return;
1367
1368 for (hwirq = 0 ; hwirq < I2C_ADDR_7BITS_COUNT ; hwirq++)
1369 irq_dispose_mapping(irq_find_mapping(domain, hwirq));
1370
1371 irq_domain_remove(domain);
1372 adap->host_notify_domain = NULL;
1373 }
1374
i2c_host_notify_irq_map(struct irq_domain * h,unsigned int virq,irq_hw_number_t hw_irq_num)1375 static int i2c_host_notify_irq_map(struct irq_domain *h,
1376 unsigned int virq,
1377 irq_hw_number_t hw_irq_num)
1378 {
1379 irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
1380
1381 return 0;
1382 }
1383
1384 static const struct irq_domain_ops i2c_host_notify_irq_ops = {
1385 .map = i2c_host_notify_irq_map,
1386 };
1387
i2c_setup_host_notify_irq_domain(struct i2c_adapter * adap)1388 static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap)
1389 {
1390 struct irq_domain *domain;
1391
1392 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY))
1393 return 0;
1394
1395 domain = irq_domain_create_linear(adap->dev.parent->fwnode,
1396 I2C_ADDR_7BITS_COUNT,
1397 &i2c_host_notify_irq_ops, adap);
1398 if (!domain)
1399 return -ENOMEM;
1400
1401 adap->host_notify_domain = domain;
1402
1403 return 0;
1404 }
1405
1406 /**
1407 * i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct
1408 * I2C client.
1409 * @adap: the adapter
1410 * @addr: the I2C address of the notifying device
1411 * Context: can't sleep
1412 *
1413 * Helper function to be called from an I2C bus driver's interrupt
1414 * handler. It will schedule the Host Notify IRQ.
1415 */
i2c_handle_smbus_host_notify(struct i2c_adapter * adap,unsigned short addr)1416 int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
1417 {
1418 int irq;
1419
1420 if (!adap)
1421 return -EINVAL;
1422
1423 irq = irq_find_mapping(adap->host_notify_domain, addr);
1424 if (irq <= 0)
1425 return -ENXIO;
1426
1427 generic_handle_irq_safe(irq);
1428
1429 return 0;
1430 }
1431 EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify);
1432
i2c_register_adapter(struct i2c_adapter * adap)1433 static int i2c_register_adapter(struct i2c_adapter *adap)
1434 {
1435 int res = -EINVAL;
1436
1437 /* Can't register until after driver model init */
1438 if (WARN_ON(!is_registered)) {
1439 res = -EAGAIN;
1440 goto out_list;
1441 }
1442
1443 /* Sanity checks */
1444 if (WARN(!adap->name[0], "i2c adapter has no name"))
1445 goto out_list;
1446
1447 if (!adap->algo) {
1448 pr_err("adapter '%s': no algo supplied!\n", adap->name);
1449 goto out_list;
1450 }
1451
1452 if (!adap->lock_ops)
1453 adap->lock_ops = &i2c_adapter_lock_ops;
1454
1455 adap->locked_flags = 0;
1456 rt_mutex_init(&adap->bus_lock);
1457 rt_mutex_init(&adap->mux_lock);
1458 mutex_init(&adap->userspace_clients_lock);
1459 INIT_LIST_HEAD(&adap->userspace_clients);
1460
1461 /* Set default timeout to 1 second if not already set */
1462 if (adap->timeout == 0)
1463 adap->timeout = HZ;
1464
1465 /* register soft irqs for Host Notify */
1466 res = i2c_setup_host_notify_irq_domain(adap);
1467 if (res) {
1468 pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n",
1469 adap->name, res);
1470 goto out_list;
1471 }
1472
1473 dev_set_name(&adap->dev, "i2c-%d", adap->nr);
1474 adap->dev.bus = &i2c_bus_type;
1475 adap->dev.type = &i2c_adapter_type;
1476 res = device_register(&adap->dev);
1477 if (res) {
1478 pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
1479 goto out_list;
1480 }
1481
1482 res = i2c_setup_smbus_alert(adap);
1483 if (res)
1484 goto out_reg;
1485
1486 device_enable_async_suspend(&adap->dev);
1487 pm_runtime_no_callbacks(&adap->dev);
1488 pm_suspend_ignore_children(&adap->dev, true);
1489 pm_runtime_enable(&adap->dev);
1490
1491 res = i2c_init_recovery(adap);
1492 if (res == -EPROBE_DEFER)
1493 goto out_reg;
1494
1495 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
1496
1497 #ifdef CONFIG_I2C_COMPAT
1498 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
1499 adap->dev.parent);
1500 if (res)
1501 dev_warn(&adap->dev,
1502 "Failed to create compatibility class link\n");
1503 #endif
1504
1505 /* create pre-declared device nodes */
1506 of_i2c_register_devices(adap);
1507 i2c_acpi_install_space_handler(adap);
1508 i2c_acpi_register_devices(adap);
1509
1510 if (adap->nr < __i2c_first_dynamic_bus_num)
1511 i2c_scan_static_board_info(adap);
1512
1513 /* Notify drivers */
1514 mutex_lock(&core_lock);
1515 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
1516 mutex_unlock(&core_lock);
1517
1518 return 0;
1519
1520 out_reg:
1521 init_completion(&adap->dev_released);
1522 device_unregister(&adap->dev);
1523 wait_for_completion(&adap->dev_released);
1524 out_list:
1525 mutex_lock(&core_lock);
1526 idr_remove(&i2c_adapter_idr, adap->nr);
1527 mutex_unlock(&core_lock);
1528 return res;
1529 }
1530
1531 /**
1532 * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
1533 * @adap: the adapter to register (with adap->nr initialized)
1534 * Context: can sleep
1535 *
1536 * See i2c_add_numbered_adapter() for details.
1537 */
__i2c_add_numbered_adapter(struct i2c_adapter * adap)1538 static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
1539 {
1540 int id;
1541
1542 mutex_lock(&core_lock);
1543 id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1, GFP_KERNEL);
1544 mutex_unlock(&core_lock);
1545 if (WARN(id < 0, "couldn't get idr"))
1546 return id == -ENOSPC ? -EBUSY : id;
1547
1548 return i2c_register_adapter(adap);
1549 }
1550
1551 /**
1552 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
1553 * @adapter: the adapter to add
1554 * Context: can sleep
1555 *
1556 * This routine is used to declare an I2C adapter when its bus number
1557 * doesn't matter or when its bus number is specified by an dt alias.
1558 * Examples of bases when the bus number doesn't matter: I2C adapters
1559 * dynamically added by USB links or PCI plugin cards.
1560 *
1561 * When this returns zero, a new bus number was allocated and stored
1562 * in adap->nr, and the specified adapter became available for clients.
1563 * Otherwise, a negative errno value is returned.
1564 */
i2c_add_adapter(struct i2c_adapter * adapter)1565 int i2c_add_adapter(struct i2c_adapter *adapter)
1566 {
1567 struct device *dev = &adapter->dev;
1568 int id;
1569
1570 if (dev->of_node) {
1571 id = of_alias_get_id(dev->of_node, "i2c");
1572 if (id >= 0) {
1573 adapter->nr = id;
1574 return __i2c_add_numbered_adapter(adapter);
1575 }
1576 }
1577
1578 mutex_lock(&core_lock);
1579 id = idr_alloc(&i2c_adapter_idr, adapter,
1580 __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
1581 mutex_unlock(&core_lock);
1582 if (WARN(id < 0, "couldn't get idr"))
1583 return id;
1584
1585 adapter->nr = id;
1586
1587 return i2c_register_adapter(adapter);
1588 }
1589 EXPORT_SYMBOL(i2c_add_adapter);
1590
1591 /**
1592 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
1593 * @adap: the adapter to register (with adap->nr initialized)
1594 * Context: can sleep
1595 *
1596 * This routine is used to declare an I2C adapter when its bus number
1597 * matters. For example, use it for I2C adapters from system-on-chip CPUs,
1598 * or otherwise built in to the system's mainboard, and where i2c_board_info
1599 * is used to properly configure I2C devices.
1600 *
1601 * If the requested bus number is set to -1, then this function will behave
1602 * identically to i2c_add_adapter, and will dynamically assign a bus number.
1603 *
1604 * If no devices have pre-been declared for this bus, then be sure to
1605 * register the adapter before any dynamically allocated ones. Otherwise
1606 * the required bus ID may not be available.
1607 *
1608 * When this returns zero, the specified adapter became available for
1609 * clients using the bus number provided in adap->nr. Also, the table
1610 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
1611 * and the appropriate driver model device nodes are created. Otherwise, a
1612 * negative errno value is returned.
1613 */
i2c_add_numbered_adapter(struct i2c_adapter * adap)1614 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
1615 {
1616 if (adap->nr == -1) /* -1 means dynamically assign bus id */
1617 return i2c_add_adapter(adap);
1618
1619 return __i2c_add_numbered_adapter(adap);
1620 }
1621 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
1622
i2c_do_del_adapter(struct i2c_driver * driver,struct i2c_adapter * adapter)1623 static void i2c_do_del_adapter(struct i2c_driver *driver,
1624 struct i2c_adapter *adapter)
1625 {
1626 struct i2c_client *client, *_n;
1627
1628 /* Remove the devices we created ourselves as the result of hardware
1629 * probing (using a driver's detect method) */
1630 list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1631 if (client->adapter == adapter) {
1632 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1633 client->name, client->addr);
1634 list_del(&client->detected);
1635 i2c_unregister_device(client);
1636 }
1637 }
1638 }
1639
__unregister_client(struct device * dev,void * dummy)1640 static int __unregister_client(struct device *dev, void *dummy)
1641 {
1642 struct i2c_client *client = i2c_verify_client(dev);
1643 if (client && strcmp(client->name, "dummy"))
1644 i2c_unregister_device(client);
1645 return 0;
1646 }
1647
__unregister_dummy(struct device * dev,void * dummy)1648 static int __unregister_dummy(struct device *dev, void *dummy)
1649 {
1650 struct i2c_client *client = i2c_verify_client(dev);
1651 i2c_unregister_device(client);
1652 return 0;
1653 }
1654
__process_removed_adapter(struct device_driver * d,void * data)1655 static int __process_removed_adapter(struct device_driver *d, void *data)
1656 {
1657 i2c_do_del_adapter(to_i2c_driver(d), data);
1658 return 0;
1659 }
1660
1661 /**
1662 * i2c_del_adapter - unregister I2C adapter
1663 * @adap: the adapter being unregistered
1664 * Context: can sleep
1665 *
1666 * This unregisters an I2C adapter which was previously registered
1667 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1668 */
i2c_del_adapter(struct i2c_adapter * adap)1669 void i2c_del_adapter(struct i2c_adapter *adap)
1670 {
1671 struct i2c_adapter *found;
1672 struct i2c_client *client, *next;
1673
1674 /* First make sure that this adapter was ever added */
1675 mutex_lock(&core_lock);
1676 found = idr_find(&i2c_adapter_idr, adap->nr);
1677 mutex_unlock(&core_lock);
1678 if (found != adap) {
1679 pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
1680 return;
1681 }
1682
1683 i2c_acpi_remove_space_handler(adap);
1684 /* Tell drivers about this removal */
1685 mutex_lock(&core_lock);
1686 bus_for_each_drv(&i2c_bus_type, NULL, adap,
1687 __process_removed_adapter);
1688 mutex_unlock(&core_lock);
1689
1690 /* Remove devices instantiated from sysfs */
1691 mutex_lock_nested(&adap->userspace_clients_lock,
1692 i2c_adapter_depth(adap));
1693 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1694 detected) {
1695 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1696 client->addr);
1697 list_del(&client->detected);
1698 i2c_unregister_device(client);
1699 }
1700 mutex_unlock(&adap->userspace_clients_lock);
1701
1702 /* Detach any active clients. This can't fail, thus we do not
1703 * check the returned value. This is a two-pass process, because
1704 * we can't remove the dummy devices during the first pass: they
1705 * could have been instantiated by real devices wishing to clean
1706 * them up properly, so we give them a chance to do that first. */
1707 device_for_each_child(&adap->dev, NULL, __unregister_client);
1708 device_for_each_child(&adap->dev, NULL, __unregister_dummy);
1709
1710 #ifdef CONFIG_I2C_COMPAT
1711 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1712 adap->dev.parent);
1713 #endif
1714
1715 /* device name is gone after device_unregister */
1716 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1717
1718 pm_runtime_disable(&adap->dev);
1719
1720 i2c_host_notify_irq_teardown(adap);
1721
1722 /* wait until all references to the device are gone
1723 *
1724 * FIXME: This is old code and should ideally be replaced by an
1725 * alternative which results in decoupling the lifetime of the struct
1726 * device from the i2c_adapter, like spi or netdev do. Any solution
1727 * should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled!
1728 */
1729 init_completion(&adap->dev_released);
1730 device_unregister(&adap->dev);
1731 wait_for_completion(&adap->dev_released);
1732
1733 /* free bus id */
1734 mutex_lock(&core_lock);
1735 idr_remove(&i2c_adapter_idr, adap->nr);
1736 mutex_unlock(&core_lock);
1737
1738 /* Clear the device structure in case this adapter is ever going to be
1739 added again */
1740 memset(&adap->dev, 0, sizeof(adap->dev));
1741 }
1742 EXPORT_SYMBOL(i2c_del_adapter);
1743
devm_i2c_del_adapter(void * adapter)1744 static void devm_i2c_del_adapter(void *adapter)
1745 {
1746 i2c_del_adapter(adapter);
1747 }
1748
1749 /**
1750 * devm_i2c_add_adapter - device-managed variant of i2c_add_adapter()
1751 * @dev: managing device for adding this I2C adapter
1752 * @adapter: the adapter to add
1753 * Context: can sleep
1754 *
1755 * Add adapter with dynamic bus number, same with i2c_add_adapter()
1756 * but the adapter will be auto deleted on driver detach.
1757 */
devm_i2c_add_adapter(struct device * dev,struct i2c_adapter * adapter)1758 int devm_i2c_add_adapter(struct device *dev, struct i2c_adapter *adapter)
1759 {
1760 int ret;
1761
1762 ret = i2c_add_adapter(adapter);
1763 if (ret)
1764 return ret;
1765
1766 return devm_add_action_or_reset(dev, devm_i2c_del_adapter, adapter);
1767 }
1768 EXPORT_SYMBOL_GPL(devm_i2c_add_adapter);
1769
i2c_parse_timing(struct device * dev,char * prop_name,u32 * cur_val_p,u32 def_val,bool use_def)1770 static void i2c_parse_timing(struct device *dev, char *prop_name, u32 *cur_val_p,
1771 u32 def_val, bool use_def)
1772 {
1773 int ret;
1774
1775 ret = device_property_read_u32(dev, prop_name, cur_val_p);
1776 if (ret && use_def)
1777 *cur_val_p = def_val;
1778
1779 dev_dbg(dev, "%s: %u\n", prop_name, *cur_val_p);
1780 }
1781
1782 /**
1783 * i2c_parse_fw_timings - get I2C related timing parameters from firmware
1784 * @dev: The device to scan for I2C timing properties
1785 * @t: the i2c_timings struct to be filled with values
1786 * @use_defaults: bool to use sane defaults derived from the I2C specification
1787 * when properties are not found, otherwise don't update
1788 *
1789 * Scan the device for the generic I2C properties describing timing parameters
1790 * for the signal and fill the given struct with the results. If a property was
1791 * not found and use_defaults was true, then maximum timings are assumed which
1792 * are derived from the I2C specification. If use_defaults is not used, the
1793 * results will be as before, so drivers can apply their own defaults before
1794 * calling this helper. The latter is mainly intended for avoiding regressions
1795 * of existing drivers which want to switch to this function. New drivers
1796 * almost always should use the defaults.
1797 */
i2c_parse_fw_timings(struct device * dev,struct i2c_timings * t,bool use_defaults)1798 void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_defaults)
1799 {
1800 bool u = use_defaults;
1801 u32 d;
1802
1803 i2c_parse_timing(dev, "clock-frequency", &t->bus_freq_hz,
1804 I2C_MAX_STANDARD_MODE_FREQ, u);
1805
1806 d = t->bus_freq_hz <= I2C_MAX_STANDARD_MODE_FREQ ? 1000 :
1807 t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? 300 : 120;
1808 i2c_parse_timing(dev, "i2c-scl-rising-time-ns", &t->scl_rise_ns, d, u);
1809
1810 d = t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? 300 : 120;
1811 i2c_parse_timing(dev, "i2c-scl-falling-time-ns", &t->scl_fall_ns, d, u);
1812
1813 i2c_parse_timing(dev, "i2c-scl-internal-delay-ns",
1814 &t->scl_int_delay_ns, 0, u);
1815 i2c_parse_timing(dev, "i2c-sda-falling-time-ns", &t->sda_fall_ns,
1816 t->scl_fall_ns, u);
1817 i2c_parse_timing(dev, "i2c-sda-hold-time-ns", &t->sda_hold_ns, 0, u);
1818 i2c_parse_timing(dev, "i2c-digital-filter-width-ns",
1819 &t->digital_filter_width_ns, 0, u);
1820 i2c_parse_timing(dev, "i2c-analog-filter-cutoff-frequency",
1821 &t->analog_filter_cutoff_freq_hz, 0, u);
1822 }
1823 EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
1824
1825 /* ------------------------------------------------------------------------- */
1826
i2c_for_each_dev(void * data,int (* fn)(struct device * dev,void * data))1827 int i2c_for_each_dev(void *data, int (*fn)(struct device *dev, void *data))
1828 {
1829 int res;
1830
1831 mutex_lock(&core_lock);
1832 res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn);
1833 mutex_unlock(&core_lock);
1834
1835 return res;
1836 }
1837 EXPORT_SYMBOL_GPL(i2c_for_each_dev);
1838
__process_new_driver(struct device * dev,void * data)1839 static int __process_new_driver(struct device *dev, void *data)
1840 {
1841 if (dev->type != &i2c_adapter_type)
1842 return 0;
1843 return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1844 }
1845
1846 /*
1847 * An i2c_driver is used with one or more i2c_client (device) nodes to access
1848 * i2c slave chips, on a bus instance associated with some i2c_adapter.
1849 */
1850
i2c_register_driver(struct module * owner,struct i2c_driver * driver)1851 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1852 {
1853 int res;
1854
1855 /* Can't register until after driver model init */
1856 if (WARN_ON(!is_registered))
1857 return -EAGAIN;
1858
1859 /* add the driver to the list of i2c drivers in the driver core */
1860 driver->driver.owner = owner;
1861 driver->driver.bus = &i2c_bus_type;
1862 INIT_LIST_HEAD(&driver->clients);
1863
1864 /* When registration returns, the driver core
1865 * will have called probe() for all matching-but-unbound devices.
1866 */
1867 res = driver_register(&driver->driver);
1868 if (res)
1869 return res;
1870
1871 pr_debug("driver [%s] registered\n", driver->driver.name);
1872
1873 /* Walk the adapters that are already present */
1874 i2c_for_each_dev(driver, __process_new_driver);
1875
1876 return 0;
1877 }
1878 EXPORT_SYMBOL(i2c_register_driver);
1879
__process_removed_driver(struct device * dev,void * data)1880 static int __process_removed_driver(struct device *dev, void *data)
1881 {
1882 if (dev->type == &i2c_adapter_type)
1883 i2c_do_del_adapter(data, to_i2c_adapter(dev));
1884 return 0;
1885 }
1886
1887 /**
1888 * i2c_del_driver - unregister I2C driver
1889 * @driver: the driver being unregistered
1890 * Context: can sleep
1891 */
i2c_del_driver(struct i2c_driver * driver)1892 void i2c_del_driver(struct i2c_driver *driver)
1893 {
1894 i2c_for_each_dev(driver, __process_removed_driver);
1895
1896 driver_unregister(&driver->driver);
1897 pr_debug("driver [%s] unregistered\n", driver->driver.name);
1898 }
1899 EXPORT_SYMBOL(i2c_del_driver);
1900
1901 /* ------------------------------------------------------------------------- */
1902
1903 struct i2c_cmd_arg {
1904 unsigned cmd;
1905 void *arg;
1906 };
1907
i2c_cmd(struct device * dev,void * _arg)1908 static int i2c_cmd(struct device *dev, void *_arg)
1909 {
1910 struct i2c_client *client = i2c_verify_client(dev);
1911 struct i2c_cmd_arg *arg = _arg;
1912 struct i2c_driver *driver;
1913
1914 if (!client || !client->dev.driver)
1915 return 0;
1916
1917 driver = to_i2c_driver(client->dev.driver);
1918 if (driver->command)
1919 driver->command(client, arg->cmd, arg->arg);
1920 return 0;
1921 }
1922
i2c_clients_command(struct i2c_adapter * adap,unsigned int cmd,void * arg)1923 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1924 {
1925 struct i2c_cmd_arg cmd_arg;
1926
1927 cmd_arg.cmd = cmd;
1928 cmd_arg.arg = arg;
1929 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1930 }
1931 EXPORT_SYMBOL(i2c_clients_command);
1932
i2c_init(void)1933 static int __init i2c_init(void)
1934 {
1935 int retval;
1936
1937 retval = of_alias_get_highest_id("i2c");
1938
1939 down_write(&__i2c_board_lock);
1940 if (retval >= __i2c_first_dynamic_bus_num)
1941 __i2c_first_dynamic_bus_num = retval + 1;
1942 up_write(&__i2c_board_lock);
1943
1944 retval = bus_register(&i2c_bus_type);
1945 if (retval)
1946 return retval;
1947
1948 is_registered = true;
1949
1950 #ifdef CONFIG_I2C_COMPAT
1951 i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1952 if (!i2c_adapter_compat_class) {
1953 retval = -ENOMEM;
1954 goto bus_err;
1955 }
1956 #endif
1957 retval = i2c_add_driver(&dummy_driver);
1958 if (retval)
1959 goto class_err;
1960
1961 if (IS_ENABLED(CONFIG_OF_DYNAMIC))
1962 WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier));
1963 if (IS_ENABLED(CONFIG_ACPI))
1964 WARN_ON(acpi_reconfig_notifier_register(&i2c_acpi_notifier));
1965
1966 return 0;
1967
1968 class_err:
1969 #ifdef CONFIG_I2C_COMPAT
1970 class_compat_unregister(i2c_adapter_compat_class);
1971 bus_err:
1972 #endif
1973 is_registered = false;
1974 bus_unregister(&i2c_bus_type);
1975 return retval;
1976 }
1977
i2c_exit(void)1978 static void __exit i2c_exit(void)
1979 {
1980 if (IS_ENABLED(CONFIG_ACPI))
1981 WARN_ON(acpi_reconfig_notifier_unregister(&i2c_acpi_notifier));
1982 if (IS_ENABLED(CONFIG_OF_DYNAMIC))
1983 WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier));
1984 i2c_del_driver(&dummy_driver);
1985 #ifdef CONFIG_I2C_COMPAT
1986 class_compat_unregister(i2c_adapter_compat_class);
1987 #endif
1988 bus_unregister(&i2c_bus_type);
1989 tracepoint_synchronize_unregister();
1990 }
1991
1992 /* We must initialize early, because some subsystems register i2c drivers
1993 * in subsys_initcall() code, but are linked (and initialized) before i2c.
1994 */
1995 postcore_initcall(i2c_init);
1996 module_exit(i2c_exit);
1997
1998 /* ----------------------------------------------------
1999 * the functional interface to the i2c busses.
2000 * ----------------------------------------------------
2001 */
2002
2003 /* Check if val is exceeding the quirk IFF quirk is non 0 */
2004 #define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
2005
i2c_quirk_error(struct i2c_adapter * adap,struct i2c_msg * msg,char * err_msg)2006 static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
2007 {
2008 dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
2009 err_msg, msg->addr, msg->len,
2010 msg->flags & I2C_M_RD ? "read" : "write");
2011 return -EOPNOTSUPP;
2012 }
2013
i2c_check_for_quirks(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)2014 static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
2015 {
2016 const struct i2c_adapter_quirks *q = adap->quirks;
2017 int max_num = q->max_num_msgs, i;
2018 bool do_len_check = true;
2019
2020 if (q->flags & I2C_AQ_COMB) {
2021 max_num = 2;
2022
2023 /* special checks for combined messages */
2024 if (num == 2) {
2025 if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD)
2026 return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write");
2027
2028 if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD))
2029 return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read");
2030
2031 if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr)
2032 return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr");
2033
2034 if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len))
2035 return i2c_quirk_error(adap, &msgs[0], "msg too long");
2036
2037 if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len))
2038 return i2c_quirk_error(adap, &msgs[1], "msg too long");
2039
2040 do_len_check = false;
2041 }
2042 }
2043
2044 if (i2c_quirk_exceeded(num, max_num))
2045 return i2c_quirk_error(adap, &msgs[0], "too many messages");
2046
2047 for (i = 0; i < num; i++) {
2048 u16 len = msgs[i].len;
2049
2050 if (msgs[i].flags & I2C_M_RD) {
2051 if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
2052 return i2c_quirk_error(adap, &msgs[i], "msg too long");
2053
2054 if (q->flags & I2C_AQ_NO_ZERO_LEN_READ && len == 0)
2055 return i2c_quirk_error(adap, &msgs[i], "no zero length");
2056 } else {
2057 if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
2058 return i2c_quirk_error(adap, &msgs[i], "msg too long");
2059
2060 if (q->flags & I2C_AQ_NO_ZERO_LEN_WRITE && len == 0)
2061 return i2c_quirk_error(adap, &msgs[i], "no zero length");
2062 }
2063 }
2064
2065 return 0;
2066 }
2067
2068 /**
2069 * __i2c_transfer - unlocked flavor of i2c_transfer
2070 * @adap: Handle to I2C bus
2071 * @msgs: One or more messages to execute before STOP is issued to
2072 * terminate the operation; each message begins with a START.
2073 * @num: Number of messages to be executed.
2074 *
2075 * Returns negative errno, else the number of messages executed.
2076 *
2077 * Adapter lock must be held when calling this function. No debug logging
2078 * takes place. adap->algo->master_xfer existence isn't checked.
2079 */
__i2c_transfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)2080 int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
2081 {
2082 unsigned long orig_jiffies;
2083 int ret, try;
2084
2085 if (WARN_ON(!msgs || num < 1))
2086 return -EINVAL;
2087
2088 ret = __i2c_check_suspended(adap);
2089 if (ret)
2090 return ret;
2091
2092 if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
2093 return -EOPNOTSUPP;
2094
2095 /*
2096 * i2c_trace_msg_key gets enabled when tracepoint i2c_transfer gets
2097 * enabled. This is an efficient way of keeping the for-loop from
2098 * being executed when not needed.
2099 */
2100 if (static_branch_unlikely(&i2c_trace_msg_key)) {
2101 int i;
2102 for (i = 0; i < num; i++)
2103 if (msgs[i].flags & I2C_M_RD)
2104 trace_i2c_read(adap, &msgs[i], i);
2105 else
2106 trace_i2c_write(adap, &msgs[i], i);
2107 }
2108
2109 /* Retry automatically on arbitration loss */
2110 orig_jiffies = jiffies;
2111 for (ret = 0, try = 0; try <= adap->retries; try++) {
2112 if (i2c_in_atomic_xfer_mode() && adap->algo->master_xfer_atomic)
2113 ret = adap->algo->master_xfer_atomic(adap, msgs, num);
2114 else
2115 ret = adap->algo->master_xfer(adap, msgs, num);
2116
2117 if (ret != -EAGAIN)
2118 break;
2119 if (time_after(jiffies, orig_jiffies + adap->timeout))
2120 break;
2121 }
2122
2123 if (static_branch_unlikely(&i2c_trace_msg_key)) {
2124 int i;
2125 for (i = 0; i < ret; i++)
2126 if (msgs[i].flags & I2C_M_RD)
2127 trace_i2c_reply(adap, &msgs[i], i);
2128 trace_i2c_result(adap, num, ret);
2129 }
2130
2131 return ret;
2132 }
2133 EXPORT_SYMBOL(__i2c_transfer);
2134
2135 /**
2136 * i2c_transfer - execute a single or combined I2C message
2137 * @adap: Handle to I2C bus
2138 * @msgs: One or more messages to execute before STOP is issued to
2139 * terminate the operation; each message begins with a START.
2140 * @num: Number of messages to be executed.
2141 *
2142 * Returns negative errno, else the number of messages executed.
2143 *
2144 * Note that there is no requirement that each message be sent to
2145 * the same slave address, although that is the most common model.
2146 */
i2c_transfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)2147 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
2148 {
2149 int ret;
2150
2151 if (!adap->algo->master_xfer) {
2152 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
2153 return -EOPNOTSUPP;
2154 }
2155
2156 /* REVISIT the fault reporting model here is weak:
2157 *
2158 * - When we get an error after receiving N bytes from a slave,
2159 * there is no way to report "N".
2160 *
2161 * - When we get a NAK after transmitting N bytes to a slave,
2162 * there is no way to report "N" ... or to let the master
2163 * continue executing the rest of this combined message, if
2164 * that's the appropriate response.
2165 *
2166 * - When for example "num" is two and we successfully complete
2167 * the first message but get an error part way through the
2168 * second, it's unclear whether that should be reported as
2169 * one (discarding status on the second message) or errno
2170 * (discarding status on the first one).
2171 */
2172 ret = __i2c_lock_bus_helper(adap);
2173 if (ret)
2174 return ret;
2175
2176 ret = __i2c_transfer(adap, msgs, num);
2177 i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
2178
2179 return ret;
2180 }
2181 EXPORT_SYMBOL(i2c_transfer);
2182
2183 /**
2184 * i2c_transfer_buffer_flags - issue a single I2C message transferring data
2185 * to/from a buffer
2186 * @client: Handle to slave device
2187 * @buf: Where the data is stored
2188 * @count: How many bytes to transfer, must be less than 64k since msg.len is u16
2189 * @flags: The flags to be used for the message, e.g. I2C_M_RD for reads
2190 *
2191 * Returns negative errno, or else the number of bytes transferred.
2192 */
i2c_transfer_buffer_flags(const struct i2c_client * client,char * buf,int count,u16 flags)2193 int i2c_transfer_buffer_flags(const struct i2c_client *client, char *buf,
2194 int count, u16 flags)
2195 {
2196 int ret;
2197 struct i2c_msg msg = {
2198 .addr = client->addr,
2199 .flags = flags | (client->flags & I2C_M_TEN),
2200 .len = count,
2201 .buf = buf,
2202 };
2203
2204 ret = i2c_transfer(client->adapter, &msg, 1);
2205
2206 /*
2207 * If everything went ok (i.e. 1 msg transferred), return #bytes
2208 * transferred, else error code.
2209 */
2210 return (ret == 1) ? count : ret;
2211 }
2212 EXPORT_SYMBOL(i2c_transfer_buffer_flags);
2213
2214 /**
2215 * i2c_get_device_id - get manufacturer, part id and die revision of a device
2216 * @client: The device to query
2217 * @id: The queried information
2218 *
2219 * Returns negative errno on error, zero on success.
2220 */
i2c_get_device_id(const struct i2c_client * client,struct i2c_device_identity * id)2221 int i2c_get_device_id(const struct i2c_client *client,
2222 struct i2c_device_identity *id)
2223 {
2224 struct i2c_adapter *adap = client->adapter;
2225 union i2c_smbus_data raw_id;
2226 int ret;
2227
2228 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
2229 return -EOPNOTSUPP;
2230
2231 raw_id.block[0] = 3;
2232 ret = i2c_smbus_xfer(adap, I2C_ADDR_DEVICE_ID, 0,
2233 I2C_SMBUS_READ, client->addr << 1,
2234 I2C_SMBUS_I2C_BLOCK_DATA, &raw_id);
2235 if (ret)
2236 return ret;
2237
2238 id->manufacturer_id = (raw_id.block[1] << 4) | (raw_id.block[2] >> 4);
2239 id->part_id = ((raw_id.block[2] & 0xf) << 5) | (raw_id.block[3] >> 3);
2240 id->die_revision = raw_id.block[3] & 0x7;
2241 return 0;
2242 }
2243 EXPORT_SYMBOL_GPL(i2c_get_device_id);
2244
2245 /* ----------------------------------------------------
2246 * the i2c address scanning function
2247 * Will not work for 10-bit addresses!
2248 * ----------------------------------------------------
2249 */
2250
2251 /*
2252 * Legacy default probe function, mostly relevant for SMBus. The default
2253 * probe method is a quick write, but it is known to corrupt the 24RF08
2254 * EEPROMs due to a state machine bug, and could also irreversibly
2255 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
2256 * we use a short byte read instead. Also, some bus drivers don't implement
2257 * quick write, so we fallback to a byte read in that case too.
2258 * On x86, there is another special case for FSC hardware monitoring chips,
2259 * which want regular byte reads (address 0x73.) Fortunately, these are the
2260 * only known chips using this I2C address on PC hardware.
2261 * Returns 1 if probe succeeded, 0 if not.
2262 */
i2c_default_probe(struct i2c_adapter * adap,unsigned short addr)2263 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
2264 {
2265 int err;
2266 union i2c_smbus_data dummy;
2267
2268 #ifdef CONFIG_X86
2269 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
2270 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
2271 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2272 I2C_SMBUS_BYTE_DATA, &dummy);
2273 else
2274 #endif
2275 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
2276 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
2277 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
2278 I2C_SMBUS_QUICK, NULL);
2279 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
2280 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2281 I2C_SMBUS_BYTE, &dummy);
2282 else {
2283 dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
2284 addr);
2285 err = -EOPNOTSUPP;
2286 }
2287
2288 return err >= 0;
2289 }
2290
i2c_detect_address(struct i2c_client * temp_client,struct i2c_driver * driver)2291 static int i2c_detect_address(struct i2c_client *temp_client,
2292 struct i2c_driver *driver)
2293 {
2294 struct i2c_board_info info;
2295 struct i2c_adapter *adapter = temp_client->adapter;
2296 int addr = temp_client->addr;
2297 int err;
2298
2299 /* Make sure the address is valid */
2300 err = i2c_check_7bit_addr_validity_strict(addr);
2301 if (err) {
2302 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
2303 addr);
2304 return err;
2305 }
2306
2307 /* Skip if already in use (7 bit, no need to encode flags) */
2308 if (i2c_check_addr_busy(adapter, addr))
2309 return 0;
2310
2311 /* Make sure there is something at this address */
2312 if (!i2c_default_probe(adapter, addr))
2313 return 0;
2314
2315 /* Finally call the custom detection function */
2316 memset(&info, 0, sizeof(struct i2c_board_info));
2317 info.addr = addr;
2318 err = driver->detect(temp_client, &info);
2319 if (err) {
2320 /* -ENODEV is returned if the detection fails. We catch it
2321 here as this isn't an error. */
2322 return err == -ENODEV ? 0 : err;
2323 }
2324
2325 /* Consistency check */
2326 if (info.type[0] == '\0') {
2327 dev_err(&adapter->dev,
2328 "%s detection function provided no name for 0x%x\n",
2329 driver->driver.name, addr);
2330 } else {
2331 struct i2c_client *client;
2332
2333 /* Detection succeeded, instantiate the device */
2334 if (adapter->class & I2C_CLASS_DEPRECATED)
2335 dev_warn(&adapter->dev,
2336 "This adapter will soon drop class based instantiation of devices. "
2337 "Please make sure client 0x%02x gets instantiated by other means. "
2338 "Check 'Documentation/i2c/instantiating-devices.rst' for details.\n",
2339 info.addr);
2340
2341 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
2342 info.type, info.addr);
2343 client = i2c_new_client_device(adapter, &info);
2344 if (!IS_ERR(client))
2345 list_add_tail(&client->detected, &driver->clients);
2346 else
2347 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
2348 info.type, info.addr);
2349 }
2350 return 0;
2351 }
2352
i2c_detect(struct i2c_adapter * adapter,struct i2c_driver * driver)2353 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
2354 {
2355 const unsigned short *address_list;
2356 struct i2c_client *temp_client;
2357 int i, err = 0;
2358
2359 address_list = driver->address_list;
2360 if (!driver->detect || !address_list)
2361 return 0;
2362
2363 /* Warn that the adapter lost class based instantiation */
2364 if (adapter->class == I2C_CLASS_DEPRECATED) {
2365 dev_dbg(&adapter->dev,
2366 "This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. "
2367 "If you need it, check 'Documentation/i2c/instantiating-devices.rst' for alternatives.\n",
2368 driver->driver.name);
2369 return 0;
2370 }
2371
2372 /* Stop here if the classes do not match */
2373 if (!(adapter->class & driver->class))
2374 return 0;
2375
2376 /* Set up a temporary client to help detect callback */
2377 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
2378 if (!temp_client)
2379 return -ENOMEM;
2380 temp_client->adapter = adapter;
2381
2382 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
2383 dev_dbg(&adapter->dev,
2384 "found normal entry for adapter %d, addr 0x%02x\n",
2385 i2c_adapter_id(adapter), address_list[i]);
2386 temp_client->addr = address_list[i];
2387 err = i2c_detect_address(temp_client, driver);
2388 if (unlikely(err))
2389 break;
2390 }
2391
2392 kfree(temp_client);
2393 return err;
2394 }
2395
i2c_probe_func_quick_read(struct i2c_adapter * adap,unsigned short addr)2396 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
2397 {
2398 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2399 I2C_SMBUS_QUICK, NULL) >= 0;
2400 }
2401 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
2402
2403 struct i2c_client *
i2c_new_scanned_device(struct i2c_adapter * adap,struct i2c_board_info * info,unsigned short const * addr_list,int (* probe)(struct i2c_adapter * adap,unsigned short addr))2404 i2c_new_scanned_device(struct i2c_adapter *adap,
2405 struct i2c_board_info *info,
2406 unsigned short const *addr_list,
2407 int (*probe)(struct i2c_adapter *adap, unsigned short addr))
2408 {
2409 int i;
2410
2411 if (!probe)
2412 probe = i2c_default_probe;
2413
2414 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
2415 /* Check address validity */
2416 if (i2c_check_7bit_addr_validity_strict(addr_list[i]) < 0) {
2417 dev_warn(&adap->dev, "Invalid 7-bit address 0x%02x\n",
2418 addr_list[i]);
2419 continue;
2420 }
2421
2422 /* Check address availability (7 bit, no need to encode flags) */
2423 if (i2c_check_addr_busy(adap, addr_list[i])) {
2424 dev_dbg(&adap->dev,
2425 "Address 0x%02x already in use, not probing\n",
2426 addr_list[i]);
2427 continue;
2428 }
2429
2430 /* Test address responsiveness */
2431 if (probe(adap, addr_list[i]))
2432 break;
2433 }
2434
2435 if (addr_list[i] == I2C_CLIENT_END) {
2436 dev_dbg(&adap->dev, "Probing failed, no device found\n");
2437 return ERR_PTR(-ENODEV);
2438 }
2439
2440 info->addr = addr_list[i];
2441 return i2c_new_client_device(adap, info);
2442 }
2443 EXPORT_SYMBOL_GPL(i2c_new_scanned_device);
2444
i2c_get_adapter(int nr)2445 struct i2c_adapter *i2c_get_adapter(int nr)
2446 {
2447 struct i2c_adapter *adapter;
2448
2449 mutex_lock(&core_lock);
2450 adapter = idr_find(&i2c_adapter_idr, nr);
2451 if (!adapter)
2452 goto exit;
2453
2454 if (try_module_get(adapter->owner))
2455 get_device(&adapter->dev);
2456 else
2457 adapter = NULL;
2458
2459 exit:
2460 mutex_unlock(&core_lock);
2461 return adapter;
2462 }
2463 EXPORT_SYMBOL(i2c_get_adapter);
2464
i2c_put_adapter(struct i2c_adapter * adap)2465 void i2c_put_adapter(struct i2c_adapter *adap)
2466 {
2467 if (!adap)
2468 return;
2469
2470 module_put(adap->owner);
2471 /* Should be last, otherwise we risk use-after-free with 'adap' */
2472 put_device(&adap->dev);
2473 }
2474 EXPORT_SYMBOL(i2c_put_adapter);
2475
2476 /**
2477 * i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg
2478 * @msg: the message to be checked
2479 * @threshold: the minimum number of bytes for which using DMA makes sense.
2480 * Should at least be 1.
2481 *
2482 * Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.
2483 * Or a valid pointer to be used with DMA. After use, release it by
2484 * calling i2c_put_dma_safe_msg_buf().
2485 *
2486 * This function must only be called from process context!
2487 */
i2c_get_dma_safe_msg_buf(struct i2c_msg * msg,unsigned int threshold)2488 u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold)
2489 {
2490 /* also skip 0-length msgs for bogus thresholds of 0 */
2491 if (!threshold)
2492 pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n",
2493 msg->addr);
2494 if (msg->len < threshold || msg->len == 0)
2495 return NULL;
2496
2497 if (msg->flags & I2C_M_DMA_SAFE)
2498 return msg->buf;
2499
2500 pr_debug("using bounce buffer for addr=0x%02x, len=%d\n",
2501 msg->addr, msg->len);
2502
2503 if (msg->flags & I2C_M_RD)
2504 return kzalloc(msg->len, GFP_KERNEL);
2505 else
2506 return kmemdup(msg->buf, msg->len, GFP_KERNEL);
2507 }
2508 EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf);
2509
2510 /**
2511 * i2c_put_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg
2512 * @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL.
2513 * @msg: the message which the buffer corresponds to
2514 * @xferred: bool saying if the message was transferred
2515 */
i2c_put_dma_safe_msg_buf(u8 * buf,struct i2c_msg * msg,bool xferred)2516 void i2c_put_dma_safe_msg_buf(u8 *buf, struct i2c_msg *msg, bool xferred)
2517 {
2518 if (!buf || buf == msg->buf)
2519 return;
2520
2521 if (xferred && msg->flags & I2C_M_RD)
2522 memcpy(msg->buf, buf, msg->len);
2523
2524 kfree(buf);
2525 }
2526 EXPORT_SYMBOL_GPL(i2c_put_dma_safe_msg_buf);
2527
2528 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2529 MODULE_DESCRIPTION("I2C-Bus main module");
2530 MODULE_LICENSE("GPL");
2531